Design, implementation, and deployment of the iKP secure electronic payment system

This paper discusses the design, implementation, and deployment of a secure and practical payment system for electronic commerce on the Internet. The system is based on the iKP family of protocols-(i = 1, 2, 3)-developed at I DM Research. The protocols implement credit card-based transactions between buyers and merchants while the existing financial network is used for paym ent clearing and authorization. The protocols are extensible and can be rea dily applied to other account-based payment models, such as debit cards. Th ey are based on careful and minimal use of public-key cryptography and can be implemented in either software or hardware. Individual protocols differ in both complexity and degree of security. In addition to being both a precursor and a direct ancestor of the well-kno wn SET standard, iKP-based payment systems have been in continuous operatio n on the Internet since mid-1996. This longevity-as well as the security an d relatively c simplicity of the underlying mechanisms-makes the iKP experi ence unique. For this reason, this paper also reports on, and addresses, a number of practical issues arising in the course of implementation and real -world deployment of a secure payment system.